Pump



Sept. 15, 1964 J DE HOFF- 3,148,825

PUMP Filed March 18, 1963 2 Sheets-Sheet l IN VENTOR.

[da/rd J. 0090/) BY 42d? ve/M United States Patent The invention relates to a pump of the vacuum operated type, and more particularly to one in which the two power compartments are provided on opposite sides of a power wall and two pistons are received in compression .cylinders and attached to a common piston rod driven by the power wall. Features of the invention include the particular mechanism for controlling and actuating the valve for alternately supplying vacuum and atmospheric air to the power compartments to drive the power wall and to replenish air in the compressing cylinders to .be compressed by the pistons. Mechanism embodying the invention provides a simple and effective valve control arrangement operating in timed relation to the movement of the pump power wall and piston rod assembly which quickly reverses the connections of vacuum and atmospheric air to the power chambers to provide a minimum power loss in each operating stroke.

In the drawings:

FIGURE 1 is a cross section view of a pump mechanism embodying the invention.

FIGURE 2 is a section view of the mechanism taken in the direction of arrows 22 of FIGURE 1. FIGURE 3 is a partial section view of the mechanism taken in the direction of arrows 3-4 of FIGURE 1.

FIGURE 4 is a partial section view of the valve portion of the mechanism taken in the direction of arrows 44 of FIGURE 2.

FIGURE 5 is a partial section view of the mechanism taken in the direction of arrows 5-5 of FIGURE 1.

FIGURE 6 is a partial section view of the mechanism taken in the direction of arrows 66 of FIGURE 1.

FIGURE 7 is a partial section view of the mechanism showing other portions of the valve actuating system and generally similar to FIGURE 2 but showing the mechanism in another valve position.

FIGURE 8 is a detail view of a portion of the valve contained in the mechanism of FIGURE 1 and showing the valve face.

The pump housing 10 has a power wall 12 illustrated as a diaphragm which separates the housing into power chambers 14 and 16. A piston rod assembly 18 is con- .nected to the diaphragm 12 and extends through chambers 14 and 16. Assembly 18 has compression pistons 20 and 22 at either end which include suitable valving to be described. The pistons are respectively received for reciprocation within cylinders 24 and 26 formed in housing 10 and respectively connecting with chambers 14 and16. The cylinders, together with their respective pistons, define compression chambers 28 and 30. Each compression chamber is provided at its outer end with a check valve 32 which When open connects the associated chamber with the air pressure outlets 34 and 36. Each check valve 32 has a valve closing spring 38 which must be overcome by compression of air in the compression chambers before the check valve opens and delivers the compressed air to the compressed air outlets. Spaced flanges 40 and 42 are provided on piston rod assembly 18 in chamber 16 intermediate the diaphragm 12 and the piston 22 for actuation of the valve operating mechanism controlling the pump.

Housing 16 is provided with three ports 44, 46 and 48. Port 44 is connected to a source of vacuum through the vacuum supply passage 50. Ports 46 and 48 are arranged formed in the shaft 78. .mounted on a pin secured in housing 10. A second ice on opposite sides of port 44 and respectively connect with chambers 14 and 16. A sliding valve 52 has a cavity 54 formed therein which is always connected with port 44 and connects either port 46 or port 48 with port 44, depending upon the valve position. The port not connected with port '44 is open to atmosphere. Thus, one of the power chambers has vacuum applied to it and the other has atmospheric air applied to it, depending upon the position of valve 52. A valve carrier 56 is pivotally mounted on stud 58 which is secured to housing 10. Carrier 56 receives valve 52 therein and holds the valve in such a position that it moves arcuately upon pivotal movement of the valve carrier to alternate between the two port communication positions. As is best seen in FIGURES 3 and 4, valve 52 is loosely received in carrier 56 so that it floats between the housing 10 and the carrier, with the reduced pressure existing in cavity 54 cooperating with atmospheric pressure acting on the valve to hold the valve in light surface sealing relation to the face of housing 10 through which ports 44, 46 and 48 open. This provides a sufiicient pressure seal while minimizing power loss caused by excessive surface friction which may occur if valve 52 is spring loaded or otherwise mechanically held against housing 10. An overcenter bellcrank 60 is also pivotally mounted on stud 58 with a washer 62 between the bellcrank and the valve carrier 56. Bellcrank 60 has an arm 64 to which an overcenter spring 66 is attached. The other end of spring 66 is attached to an arm 68 of valve carrier 56. Bellcrank 60 and valve carrier 56 have their respective arms so arranged that pivotal movement of the bellcrank will pass the spring over the axis of stud 58, which is the pivoting axis of the bellcrank and the valve carrier, and spring tension will then move the valve carrier. A stop 70 is provided on the housing 10 so that it is engaged by either lug 72 or lug '74 of valve carrier 56 to provide precise positioning of the valve 52 in one of the two port communication positions. Stop 70 also provides limits for pivotal movement of bell-crank 60 when either the bellcrank arm 64 or the bellcrank lug 76 engages the stop. Arm 64 and lug 76 are so angularly positioned about the pivotal axis of the bellcrank 60 that overcenter action of spring 66 to move valve carrier 56 is obtainable from either extreme ,position of the valve carrier.

;in pivotal movement of the bellcrank 60. Shaft 78 receives the arm 84 of another bellcrank 86 in a slot 88 Bellcrank 86 is pivotally arm 92 of bellcrank 86 extends into chamber 16 so that 42 near the extreme stroke limits of the piston rod and is moved by the piston rod to reciprocate shaft 78 sufficiently to pivot bellcrank 60 so that spring 66 goes overcenter and snaps the valve carrier 56 to its other position. I

In the position shown in FIGURE 1, for example, the leftward movement of the diaphragm 12 has just moved bellcrank arm 92 clockwise by piston rod flange 42. Vacuum is being admitted into chamber 16 and atmospheric air is in chamber 14. The just completed leftward movement of flange 42 has reciprocated shaft '78 enough to move bellcrank 60 and overcenter spring 66 so that port 46 has been uncovered and port 48 has been connected with port 44. Thus, the pump has just completed its leftward stroke wherein air has been compressed in chamber 28 and the pump is about to move to the rightto compress air in chamber 30. This is accomplished by the introduction of vacuum into chamber 16 and atmospheric air into chamber 14 in the manner just described. As the piston rod assembly moves to the right, the flapper type valve )4 of piston 28 opens to admit air from chamber 14 into chamber 28, thus recharging chamber 28 for the next compression stroke. The flapper valve 96 of piston 22, on the other hand, is closed since the compression pressure in chamber St) is higher than the pressure in power chamber 16. As the air is compressed in chamber 3%, check valve 32 is opened against the force of its spring 38 and the compressed air is delivered to the outlet 36. In the meantime the check valve 32 associated with chamber 28 is closed due to the presence of positively pressurized air in outlet 34 and atmospheric air in chamber 28.

Upon completion of the rightward stroke movement, flange 40 has engaged bellcrank arm 92 of bellcrank 86 to move shaft 78 upwardly, thus moving bellcrank 60 counterclockwise as seen in FIGURE 2 and moving the overcenter spring 66 so that it causes clockwise movement of valve carrier 5% and reverses the port communication position of ports 44, 46, and 48. This is the position of the mechanism shown in FIGURE 7. Thus, leftward movement of the diaphragm 12 is initiated and the same process is carried out again.

I claim: g

1. In a pump, in combination, a housing formed with two chambers, a reciprocable piston rod in said chamhers, said housing being formed with a pair of ports for establishing communication between the chambers and the atmosphere and a third port adapted for connection to a source of vacuum, a valve carrier having a valve received therein and pivotally mounted on said housing, said valve being arranged to selectively establish communication of the third port with either of the other ports while uncovering the remaining port to the atmosphere upon pivotal movement of said carrier, said valve having an outer peripheral portion spaced from said carrier for allowing floating movement. of said valve between said housing and said carrier, one face on said valve being exposed to said third port and another face on said valve being exposed to atmosphere for producing a pressure dilferential across said valve for holding it in light surface sealing engagement with said housing, stop reciprocable shaft axially and actuate said overcenter bellcrank, means on the piston rod arranged for alter nate engagement with said bellcrank one arm to oscillate said second bellcrank at each reciprocation of the piston rod.

2. A vacuum operated pump comprising a housing having a power wall dividing said housing into a pair of actuation compartments, first and second cylinders respectively formed in said housing and connecting with said actuating compartments, a piston rod having pistons formed on the opposite ends thereof reciprocably received in said compartments and said cylinders and secured 'to said power wall for actuation thereby, valve means in each of said pistons for recharging said cylinders when the pressure in each of said cylinders is respectively less than the pressure in the power compartment connected therewith, first and second ports in said housing for establishing communication between the power compartments and the atmosphere and a third port adapted for connection to a source of vacuum, port controlling valve means movably mounted on said housing to selectively establish communication of said third port and with either of said first and second ports while uncovering the remaining port to the atmosphere, said valve having an outer peripheral portion spaced from said carrier for allowing floating movement of said valve between said housing and said carrier, one face on said valve being exposed to said third port and another face on said valve being exposed to atmosphere for producing a pressure differential across said valve for holding it in light surface sealing engagement with said housing, snap action overcenter means for selectively positioning said port controlling valve means, and means actuated by said piston rod near the opposite stroke limits thereof for actuating said valve through said overcenter snapaction means. i I

3. A valve control system for a pressure actuated reciprocable' pump having a reciprocable piston rod, said valve actuating means comprising a bellcrank alternately movable by said piston rod adjacent the outer stroke limits of said piston rod, an axially reciprocable shaft moved by said bellcrank, a pivotal arm moved by said reciprocable shaft, a valve carrier having a valve mounted therer in and an overcenter spring secured thereto and to said rier having an arm extending therefrom and an overcenter spring attached to said overcenter bellcrank arm and said valve carrier arm and selectively holdingsaid valve carrier against said stop'means in one of said port communication positions, and axially reciprocable shaft operatively connected with said overcenter bellcrank for pivoting said bellcrank to move said spring over the pivotal center of said bellcrank and said valve carrier, a

second bellcrank pivotally mounted in said housing and having one arm thereof extending into operable engagement with said piston rod and another arm thereof engaging said reciprocable shaft to reciprocably move said pivotal arm, said valve having an outer peripheral portion spaced from said carrier for allowing floating move ment of said valve between said housing and said carrier, one face on said valve being exposed to said third port and another face on said valve being exposed to atmosphere for producing a pressure differential across said valve for holding it in light surface sealing engagement with said housing, and suitable means establishing extreme positions of said valve carrier obtained by overcenter action of said overcenter spring as said reciprocable shaft reciprocates.

7 References Cited in the file of this patent UNITED STATES PATENTS Peters Oct. 2, 1962 

1. IN A PUMP, IN COMBINATION, A HOUSING FORMED WITH TWO CHAMBERS, A RECIPROCABLE PISTON ROD IN SAID CHAMBERS, SAID HOUSING BEING FORMED WITH A PAIR OF PORTS FOR ESTABLISHING COMMUNICATION BETWEEN THE CHAMBERS AND THE ATMOSPHERE AND A THIRD PORT ADAPTED FOR CONNECTION TO A SOURCE OF VACUUM, A VALVE CARRIER HAVING A VALVE RECEIVED THEREIN AND PIVOTALLY MOUNTED ON SAID HOUSING, SAID VALVE BEING ARRANGED TO SELECTIVELY ESTABLISH COMMUNICATION OF THE THIRD PORT WITH EITHER OF THE OTHER PORTS WHILE UNCOVERING THE REMAINING PORT TO THE ATMOSPHERE UPON PIVOTAL MOVEMENT OF SAID CARRIER, SAID VALVE HAVING AN OUTER PERIPHERAL PORTION SPACED FROM SAID CARRIER FOR ALLOWING FLOATING MOVEMENT OF SAID VALVE BETWEEN SAID HOUSING AND SAID CARRIER, ONE FACE ON SAID VALVE BEING EXPOSED TO SAID THIRD PORT AND ANOTHER FACE ON SAID VALVE BEING EXPOSED TO ATMOSPHERE FOR PRODUCING A PRESSURE DIFFERENTIAL ACROSS SAID VALVE FOR HOLDING IT IN LIGHT SURFACE SEALING ENGAGEMENT WITH SAID HOUSING, STOP MEANS ON SAID HOUSING FOR SELECTIVELY LIMITING CARRIER PIVOTAL MOVEMENT IN AN OPPOSITE DIRECTION TO SELECTIVELY ESTABLISH THE POSITION OF THE VALVE IN EITHER OF SAID PORT COMMUNICATION POSITIONS, AND OVERCENTER BELLCRANK PIVOTALLY MOUNTED ON SAID HOUSING ADJACENT SAID VALVE CARRIER HAVING AN ARM EXTENDING THEREFROM, SAID VALVE CARRIER HAVING AN ARM EXTENDING THEREFROM AND AN OVERCENTER SPRING ATTACHED TO SAID OVERCENTER BELLCRANK ARM AND SAID VALVE CARRIER ARM AND SELECTIVELY HOLDING SAID VALVE CARRIER AGAINST SAID STOP MEANS IN ONE OF SAID PORT COMMUNICATION POSITIONS, AND AXIALLY RECIPROCABLE SHAFT OPERATIVELY CONNECTED WITH SAID OVERCENTER BELLCRANK FOR PIVOTING SAID BELLCRANK TO MOVE SAID SPRING OVER THE PIVOTAL CENTER OF SAID BELLCRANK AND SAID VALVE CARRIER, A SECOND BELLCRANK PIVOTALLY MOUNTED IN SAID HOUSING AND HAVING ONE ARM THEREOF EXTENDING INTO OPERABLE ENGAGEMENT WITH SAID PISTON ROD AND ANOTHER ARM THEREOF ENGAGING SAID RECIPROCABLE SHAFT TO RECIPROCABLY MOVE SAID RECIPROCABLE SHAFT AXIALLY AND ACTUATE SAID OVERCENTER BELLCRANK, MEANS ON THE PISTON ROD ARRANGED FOR ALTERNATE ENGAGEMENT WITH SAID BELLCRANK ONE ARM TO OSCILLATE SAID SECOND BELLCRANK AT EACH RECIPROCATION OF THE PISTON ROD. 